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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
*
* This example shows a simple extention of an existing PARC Object implementation
* (PARCString) to replace the default implementation of the Compare() function with another.
*
* The demonstration shows how to reverse the sort order of a PARCSortedList
* containing a list of PARCString instances without changing PARCSortedList nor PARCString.
*
*/
#include <stdio.h>
#include <parc/algol/parc_SortedList.h>
#include <parc/algol/parc_String.h>
/*
* This is the default behaviour of the PARCSortedList implementation.
*/
void
forwardOrder(void)
{
PARCSortedList *sortedList = parcSortedList_Create();
PARCString *aaa = parcString_Create("aaa");
PARCString *aab = parcString_Create("aab");
PARCString *aac = parcString_Create("aac");
parcSortedList_Add(sortedList, aaa);
parcSortedList_Add(sortedList, aab);
parcSortedList_Add(sortedList, aac);
parcSortedList_Display(sortedList, 0);
parcString_Release(&aaa);
parcString_Release(&aab);
parcString_Release(&aac);
}
/*
* This function will be substituted for the default Compare implementation in the PARCString object.
*/
int
parcString_ReverseCompare(const PARCString *string, const PARCString *other)
{
return parcString_Compare(string, other) * -1;
}
parcObject_Extends(PARCReverseString, PARCString,
.compare = (PARCObjectCompare *) parcString_ReverseCompare);
PARCString *
parcMyString_Create(const char *string)
{
PARCString *result = parcString_Create(string);
// By setting the descriptor to our special descriptor here, we effectively
// substitute the default compare function with our parcString_ReverseCompare
parcObject_SetDescriptor(result, &parcObject_DescriptorName(PARCReverseString));
return result;
}
void
reverseOrder(void)
{
PARCSortedList *sortedList = parcSortedList_Create();
PARCString *aaa = parcMyString_Create("aaa");
PARCString *aab = parcMyString_Create("aab");
PARCString *aac = parcMyString_Create("aac");
parcSortedList_Add(sortedList, aaa);
parcSortedList_Add(sortedList, aab);
parcSortedList_Add(sortedList, aac);
parcSortedList_Display(sortedList, 0);
parcString_Release(&aaa);
parcString_Release(&aab);
parcString_Release(&aac);
}
int
main(int argc, const char *argv[argc])
{
forwardOrder();
reverseOrder();
return 0;
}
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